An At4060 has come up for sale around here for $695. What do you guys think of this mic?
AT4060 Tube Condenser Mic
Ty Ford
Baltimore, MD
The Audio Technica AT4060 vacuum tube microphone ($1,695) is a transformer
output, cardioid-only condenser microphone with an external power supply.
Included in the price are: a protective vinyl-coated box for the mic, the very sturdy
AT8447 all-metal suspension mount, AT8560 power supply with IEC power cord
and almost 33 feet of multi-conductor cable for connecting the mic to the power
supply. Addition accessory options include a foam screen ($48), and the 8430 clip
that also works on the 4033 or 4050 ($168). The manual suggests that you always
turn off the power supply when connecting or disconnecting the mic. I read that
after I had done both with the power supply on. I had no problem, but maybe I got
lucky.
The AT8447 suspension mount, specially made for the AT 4060, has two knobs
that tighten to hold the mic more securely than earlier mounts that use only
elastic bands. The 1U space AT8560 power supply is half-rack size and comes with
brackets for mounting in pairs. The six-pin XLR on the rear of the power supply
connects a multiconductor cable that provides power to the Sovtek 6922 tube
onboard the mic and retrieves the audio from the capsule.
The 4060 capsule is based on the 4050 and contains dual 21.3mm diaphragms
coated with 2 microns of vapor deposited gold. The diaphragm is polarized at
110VDC and backplate is at ground. The filaments run at 6.3VAC. According to
Audio Technica's Kelly Statham, the Sovtek 6922 tube is used as an impedance
converter. "There are no solid state devices in there except the power supply. The
6922 was chosen by Audio Technica-Japan. We tested a bunch of the ones with the
same number and narrowed it down to a special version of 6922 based on low noise
and having the quiescent current as close to spec as possible before we put our
own serial numbers on them." Audio Technica has been running accelerated
testing on the Sovtek tubes and has yet to see one blow.
Statham says the 4060 doesn't require additional output circuitry because the
higher capsule voltage and tighter (and aged) diaphragm results in a sufficient
output. The method for aging of the diaphragm is proprietary information, but
Statham says it's done to keep the diaphragm from stretching over time.
A closer look at the capsule reveals that it's surrounded by a ring with holes
drilled in it. "That helps to extend our low end, " says Statham, "It changes the
acoustic distance between port A and port B (backside to front side) in a cardioid
pattern, or the lines of low frequency phase. It also provides better off-axis pattern
linearity over frequency and more stable load (acoustic resistance) on the rear
port."
Attached to one side of the internal metal body frame is a rectangular metallic
flap to shield the .22 Farad filament supply filter capacitors. On the inside of the
body shell, a small piece of sheet rubber acts as a shock absorber, should the mic
be jarred, bringing the tube into contact with the shell. The area around the three
screws that hold the shell and head grille to the frame are gold plated to ensure
ground continuity from the body to the shell and head.
THE SOUND OF SILENCE
Although the AT4060's 19dB (A-weighted) self noise is higher than the Neumann
FET TLM 103 at 7dB, the AT4060 surprised me with how quiet it was -- noticeably
quieter than a Neumann U 89, U 87 and Gefell UM70. Tube mics used to get a bad
rap for how much noise the tubes generated The AT4060 is proof that tube mics
don't have to be noisey.
On male announcer voice, the AT4060 through a GML mic preamp was strong
and clear. In fact, there is none of that "warm tubey" sound that I usually only
care for when trying to mask irritatingly edgey sound sources. The extra lift on
the high end is not as detailed as the Neumann M 149 nor the Manley tube
cardioid, but significantly more detailed than the AT4050. This is not the mic to
use on sibilant sources.
On acoustic guitar, the brightness of the AT4060 gave the somewhat-dead strings
of my D28S Martin a lot more sparkle than they appeared to have in free air. In
order to minimize the bass build up due to the proximity effect, I first positioned
the mic about four inches above the body so that the capsule faced down across the
sound hole. Lots of brights, not too much bottom, but the off-axis sound was a bit
strange. Setting the mic out about 14 inches from the sound hole and twisting it to
about a 30 degree angle to keep the bass from building up resulted in a fairly
natural and balanced acoustic guitar sound.
I visited Jeff Order Productions to compare his 4050 with the 4060. Jeff uses the
preamps in his Soundtracs Solo Logic 32x8 console. We found both the 4050 (in
cardioid) and the 4060 had basically equal output levels. The mid range of both
mics was very similar, but the 4060 had a larger bottom and more detailed top
end. Both mics exhibited the same amount of reach. Pushed inside his baby
grand, it did a nice job of presenting a balanced sound, with perhaps a little too
much bottom.
At Flite 3, Louis Mills, Mark Patey and I compared the 4060 with a Neumann U 87
(not an ai). The 4060 was 6dB-8dB hotter than the U 87. After adjusting the API
preamps for equal gain, the 4060 was 4dB quieter on the meters. The meters don't
always tell the tale. The self-noise of the U 87 was higher in frequency than the
4060, making the 4060 self-noise much less apparent.
Both mics had similar reach and similar rear rejection characteristics. The
proximity effect of each mic was a little different. For voice work, the 4060 worked
well at four to five inches. In order to get the same hot spot on the Neumann, I
had to move in about an inch closer. Both mics exhibited about the same amount
of sensitivity to popping. Speaking of hot spots, both 4060's I had seemed to have
their hot spots slightly off center. On both mics, I had to move about five to ten
degrees to the right before I found the spot.
The 4060 has a brighter top end than the U 87. Mills liked the broad rise and
thought that it was not in detriment of the bass. Patey commented that the 4060
might not be the mic to use on large bass voices because the mic was obviously
sensitive to those frequencies as well. The 4060 begins a lift at 2kHz rises gently to
+4dB by 4kHz and stays there until 13kHz. From there it drops sharply to 0dB at
14kHz and is at -4dB by 15kHz. That broad rise, similar to a shelving EQ boost,
adds a lot of sparkle.
My next project was a TV voice track for a local car dealer. The job called for an
over-the-top delivery, everything turned up to eleven. I'm not sibilant, but it's easy
to "fress" when you're speaking that loud and that quickly and the 4060 did a great
job of capturing it. I applied a high-frequency shelf EQ to the final track to remove
the excess "fress."
IN CONCLUSION
Because of its increased high frequency response and low noise,
the AT4060 does not comply with the old definition of "tube sound." It is neither
murky nor "filmic." I'd be interested in hearing some comparisons between pairs
of AKG 414s and AT4060s on drum overheads. Regardless of the source, if you
regularly boost the 10kHz shelving EQ, try the AT4060, and don't reach for the EQ.
For the price point, it's a player.
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